SU1173177A1 - Device for measuring object displacement and index of transparent media refraction - Google Patents

Abstract

1. A DEVICE FOR MEASURING THE MOVEMENT OF OBJECTS AND refractive index transparent media, comprising: a source of coherent radiation, the interferometer comprising a beam splitter, a reflector, forming a measuring arm, the reflector and the modulator forming the support arm, two photoelectric converter and a computing unit coupled to the transducers, characterized in that, with whole improvements in the measurement accuracy, it is equipped with an optical element located between the beam splitter and the reflector forming the light-emitting diode itelnoe shoulder and the beam splitter arranged between the coherent light source and the interferometer. 2. The device according to n.t is characterized in that, with a chain for improving the accuracy of measuring changes in the refractive index of transparent media, the optical element is made in terms of volume with a given optical length.

Description

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WITH

The invention relates to a measuring technique, namely interference measurements, and can be used for precision measurements of object movements and changes in the refractive indices of transparent media.

The aim of the invention is to improve the measurement accuracy as well as increase the measurement accuracy of refractive index changes. transparent media

1 is a schematic diagram of a device for measuring object movements and refractive indices of transparent media | figure 2 - the mutual arrangement of the reflector of the measuring arm and the volume with a given optical length.

The device DP for measuring the movement of objects and refractive indices of transparent media contains a source 1 of coherent radiation and an interferometer 2, which includes a beam splitter 3, a reflector 4 and a modulator 5 forming the reference arm, a reflector 6 and an optical element 7 installed on the beam path, forming the measuring arm, the splitter., 8 beams, installed between the coherent radiation source 1 and the interferometer, two photoelectric converters, each of which consists of a photodetector 9 or 10 and shaper it or 12 respectively. The inputs of the formers 11 and 12 are connected to the outputs of the respective photo-receivers 9 and 10, and their codes with the computing unit 13.

The beam splitter 8 is made in the form of a prism, mainly from a birefringent material. The optical element 7 for measuring displacements is made similarly to the reflector 6, for example, in the form of a trepelprism, DP measurements of changes in the refractive index of transparent media, the optical element 7 is made in the form of a volume with a given optical length, for example, a glass column. A single-frequency laser is used.

The device works as follows.

Collimated beam of light from coherent radiation source 1

the aisle splitter pass 8 is divided into two parallel beams. The divider 3 divides each of the incident beams of light into two beams. The rays reflected from the splitter 3 are directed to the reflector 4 and the modulator 5. In the measuring arm, the rays propagate to the reflector 6 and the optical element 7 Returned from these elements, the rays are spatially combined on the splitter 3 with the corresponding rays of light returned by the splitter 4, and interfere. Interferometer formed at the output

Two two pairs of interference fields are recorded by photoreceivers 9 and 10, the electrical signals from which are converted by the formers 11 and 12 into counting pulses. These pulses come to the computing unit 13, where they are processed in accordance with a given program.

One pair of generated interference fields reflects changes in the difference in the optical lengths of the reference arm (the optical path from the beam splitter

3to the reflector 4) and the measuring arm (the optical path from the beam splitter 3 to the reflector 6). Another pair of generated interference fields reflects changes in the optical length difference between the reference arm and the measuring arm formed

by introducing the optical element 7. In the computing unit 13, the other result is constantly subtracted from the other, so that the change in the difference of the optical paths (light) in the measuring arm is recorded. When measuring linear displacements, this is the optical length between the reflectors 6 and 7.

The movement of the reflector 4 of the reference arm with the help of the modulator 5 and the change under the influence of external conditions of the refractive index of the medium (filling the space between the beam splitter 3 and the reflector 4, as well as between the beam splitter 3 and the optical element 7) lead to a synchronous change in the phases of the interference signals and the occurrence in the generator 11 and 12 of the same number of countable pulses. The difference in the number of pulses obtained in the computing unit 13 is zero, and the device shows the same change. The optical length between the reflectors 6 and 7, for example, by moving the reflector 6 of the measuring arm leads to a different change in the phases of the interference signals, that in turn, leads to the formation of a different number of counting pulses in the generator 11 and 12. According to the difference in the number of counting pulses in the computing unit 13, the magnitude of the displacement of the reflector 6 relative to the optical element is calculated 7. When measuring changes in the refractive index of transparent media, the geometric paths of the rays are the same in the measuring arm. The optical paths of the rays are different: the path of one beam (cofiGo2) passes through the medium followed by it (it changes accordingly as the refractive index changes), and the other passes through a volume with a given optical length that remains almost constant. The change in the difference of these optical paths causes various changes in the phases of the interference signals. After being converted into counting pulses and processed in the computing unit 13, the magnitude of the change in the refractive index relative to the initial (zero) reference is assigned to them. Thus, the device provides an automatic accounting of changes in the uncompensated length of the interferometer, which increases the measurement accuracy.

FIG. 2

Claims (2)

1. A DEVICE FOR MEASURING THE MOVEMENTS OF OBJECTS AND REFRACTION INDICATORS OF TRANSPARENT MEDIA, containing a coherent radiation source, an interferometer including a beam splitter, a reflector forming a measuring arm, a reflector and a modulator forming a supporting arm, two 'photovoltaic converters, and a computing converter characterized in that, in order to improve the accuracy of measurement, it is equipped with an optical element located between the beam splitter and the reflector forming the beam splitter shoulder, and a beam splitter installed between the coherent radiation source and the interferometer. 2. The device according to claim 1, characterized in that, in order to increase the accuracy of measuring changes in the refractive index of transparent media, the optical element is made in the form of a volume with a given optical length.